There are known various polymer composites such as fiber reinforced plastics utilized in civil, architectural, chemical and transportation industries. In general, these fiber reinforced plastics contain a very large amount of resin that is more than 50 vol. % of the total volume of the final product. This higher volume of resin facilitates forming by methods, such as filament winding, pultrusion, lamination etc. However, this large amount of resin leads time-dependent permanent creep deformation of fiber reinforced plastics that occurs under stress even at ambient temperature and also in moderately elevated temperatures. Furthermore, fiber reinforced plastics now face a knotty problem of how to be recycled or disposed without environmental damage. Therefore, there is a growing interest in high strength materials that could be form into shapes utilizing minimum amount of resin so that minimize the environmental damage.
The article entitled as "Fiber toughening of MDF cement" (Journal of Materials Science, 20, 1985, pp. 37-45) revealed a method for reinforcing a polymer cement composite known as the Macro Defect Free cement. Macro Defect Free cement contains very low amount of polymer, say, less than 15 vol. % of the total volume of the product. It was shown that method of lamination fiber mats between polymer cement composite sheets then followed a hot pressing at 80.degree. C. for 10 min. Stress-strain curves of this material have shown the failure of polymer cement matrix at rather lower stress, say, less than 150 MPa. In terms of bending modulus of elasticity and bending strength there were no advantages in the incorporation of fiber mats into polymer cement matrix while it has shown little improvement in strength. Furthermore, the material is very susceptible to moisture.
On the other hand, Japanese Patent Laid-Open No. 64076/1994 discloses a method of reinforcing polymer free brittle material by sticking unidirectional fiber layers on the outer surface of a brittle material substrate. However, bending strength of the final product is very low, say, lower than 30 MPa. The reason of this is lower fracture elongation of the substrate. Therefore, the material which was disclosed by Japanese Patent Laid-open No. 64076/1994 would not be work as a substitution for the fiber reinforced plastics or would not be fulfill the high strength material requirements.